[0001] The invention relates to a liquid-sealing shaft seal apparatus for a rotary electrical
machine using liquid, such as lubrication oil or seal oil, and to a rotary electrical
machine using the shaft seal apparatus.
[0002] In general, large rotary electrical machines employ slider bearings using oil as
a lubricant. In order to achieve the high efficiency, hydrogen-cooled rotary electrical
machines employ oil seals using sealing oil to seal hydrogen gas for cooling the interior
of the machine inside of the rotary electrical machine. Generally, labyrinth seals
are used to prevent lubrication oil, seal oil, or the like from leaking to the interior
or exterior of a rotary electrical machine. In this case, it is generally known that,
as an inherent structural nature of the labyrinth seal, a relatively large gap exists
between the seal and a rotation shaft of the rotary electrical machine, the fluid
may leak responsively following, for example, liquid state variations. To minimize
such leakage, measures are taken such that, for example, labyrinth seals are provided
in multiple stages, or a labyrinth seal is arranged in a position sufficiently spaced
away from a liquid source. However, according to such measures, the overall size of
the rotary electrical machine has to be increased, and also the seal performance is
not sufficient, so that it is difficult to prevent leakage of the fluid.
[0003] In recent years, in order to solve these problems, techniques are known that use
brush seals to improve seal performance (for example, refer to Jpn. Pat. Appln. KOKAI
Publication Nos. 2001-90842, 2001-295609, and 2002-303371. However, the techniques
disclosed in Jpn. Pat. Appln. KOKAI Publication Nos. 2001-90842 and 2001-295609 are
not intended to seal liquid but intended to seal gases.
[0004] In general, a conventional liquid-sealing shaft seal apparatus of a rotary electrical
machine, which uses a brush seal, has a structure shown in FIG. 6. In FIG. 6, numeral
1 denotes a rotation shaft, and numeral 2 denotes a frame forming the exterior of
the rotary electrical machine. The rotation shaft 1 is rotatably journaled by bearings
(not shown) mounted on the frame 2. Numeral 3 denotes a brush holder. The brush holder
3 is robustly and hermetically fixed to the frame 2, and is mounted in such a manner
as to close a space of the liquid atmosphere S1 (or, "liquid atmosphere space", hereafter)
and a space of the non-liquid atmosphere S2 (or, "non-liquid atmosphere space", hereafter)
in the rotary electrical machine. Numeral 4 denotes a brush seal formed in the manner
that a brush 5 is clamped by a brush clamp 6. The brush seal 4 is configured such
that multiple seal segments circumferentially split are combined into an annular state
array, and that two arrays are arranged by circumferentially shifting split planes
of the segments. Numeral 7 denotes packing formed similarly as the brush seal 4 such
that multiple packing segments circumferentially split are combined in an annular
state. The packing 7 thus formed is so mounted on an axial sidewall of the brush seal
4 that the sprit planes of the packing segments are circumferentially shifted with
respect to those of the brush seal segments. Numeral 9 denotes a holding plate fixed
with a bolt (not shown) on an axial sidewall of the brush holder 3 in order to fix
the brush seal 4 and the packing 7 on the brush holder 3. In this case, although a
single-stage brush seal apparatus has been shown and described, an example having
multiple brush seal assemblies arranged in multiple stages is disclosed in Jpn. Pat.
Appln. KOKAI Publication No. 2001-295609.
[0005] In any of Jpn. Pat. Appln. KOKAI Publication Nos. 2001-90842, 2001-295609, and 2002-303371,
the structure of the brush seal apparatus itself is not described in detail, however,
it is assumed that the shaft seal apparatus uses such a conventional brush seal of
the type as described with reference to FIG. 6. Therefore, the liquid-sealing shaft
seal apparatus thus constructed is not capable of completely preventing leakage of
a small amount of liquid through gaps of element lines of the brush 5 constituting
the brush seal 4 and through a contact face gap between the brush 5 and the rotation
shaft 1. For this reason, a case can arise in which a total leaked liquid amount exceeds
an allowable amount in a long time operation of the rotary electrical machine, thereby
causing, for example, overflow from the interior of the rotary electrical machine
or a problem in the operation of the rotary electrical machine. In addition, in the
case where, for example, the rotation shaft has vibrated or the brush seal has been
eccentrically mounted with respect to the rotation shaft, a case can arise in which
the amount of leakage of the liquid is increased and exceeds the allowable amount
in a relatively short time. Resultantly, even a case can arise in which the rotary
electrical machine cannot be operated at all.
[0006] In addition, there is a rotary electrical machine of the type that has different
liquids and that uses a shaft seal apparatus to avoid mixture of the liquids. For
example, in the construction shown in FIG. 6, a liquid different from a liquid contained
in the atmosphere space S1 can be contained in the atmosphere space S2. With such
the conventional liquid-sealing shaft seal apparatus, the liquid leaks little by little
from one of the atmosphere spaces S1 and S2 to the other, and a case takes place in
which the different liquids are mixed with one another during operation over a long
time, thereby hindering the operation of the rotary electrical machine. Also with
the structure provided with the multiple-stage brush seals according to Jpn. Pat.
Appln. KOKAI Publication No. 2001-295609, liquid leakage little by little cannot be
prevented, so that the leaked liquid fills over time in one of the brush-seal spaces
between the multiple-stage brush seals, and the liquid leaks to the next brush seal
space, thus resulting serial leakage. Thus, with the conventional brush-seal type
shaft seal apparatus, it is very difficult to prevent liquid leakage little by little
even in the construction having multiple-stage brush seals arranged.
[0007] The present invention has been made to solve the above-described problems, and an
object of the invention is to provide a liquid-sealing shaft seal apparatus and a
rotary electrical machine using the shaft seal apparatus, the shaft seal apparatus
being capable of minimizing the amount of leakage of a liquid existing in a liquid
atmosphere to a non-liquid atmosphere space of a rotary machine.
[0008] Another object of the invention is to provide a liquid-sealing shaft seal apparatus
and a rotary electrical machine using the shaft seal apparatus, the shaft seal apparatus
being capable of minimizing the amount of a mixture of different liquids in a rotary
machine containing the different liquids.
[0009] According to one aspect of the present invention, there is provided a liquid-sealing
shaft seal apparatus comprising: a rotation shaft; a plurality of brush seals arranged
in such a manner as to contact and surround the rotation shaft; and a brush holder
which holds the brush seals, wherein the brush seals are arranged through a cavity
in an axial direction of the rotation shaft, and the brush holder is provided with
a liquid returning pass to return a liquid having leaked through the brush seals into
the cavity to the side of an atmosphere in which a liquid is present as a sealing
target.
[0010] According to another aspect of the present invention, there is provided a liquid-sealing
shaft seal apparatus comprising: a rotation shaft; a plurality of brush seals arranged
in such a manner as to contact and surround the rotation shaft; and a brush holder
which holds the brush seals, wherein the brush seals are arranged through a cavity
in an axial direction of the rotation shaft; and a pressure in the cavity is higher
than a pressure on the side of an atmosphere in which a liquid is present as a sealing
target.
[0011] According to the present invention, the amount of leakage liquid leaking through
the brush seal can be reduced, and the leakage liquid having leaked to the side of
the non-liquid atmosphere through the brush seal on the side of the liquid atmosphere
can be returned to the liquid atmosphere space through the liquid returning pass.
Consequently, the amount of liquid leaking through the brush seal and accumulated
in the liquid atmosphere space can be significantly reduced.
[0012] Further, leakage liquids having leaked through the brush seals on the sides of the
respective liquid atmospheres can be accumulated without causing dispersion thereof,
and can be returned to the spaces on the sides of the liquid atmospheres through the
respective liquid returning passes. Consequently, the amounts of liquids having leaked
through the brush seals and accumulated in the spaces on the sides of the liquid atmospheres
can be significantly reduced. Further, contamination by a different liquid can be
significantly reduced.
[0013] This summary of the invention does not necessarily describe all necessary features
so that the invention may also be a sub-combination of these described features.
[0014] The invention can be more fully understood from the following detailed description
when taken in conjunction with the accompanying drawings, in which:
FIG. 1A is an axial cross-sectional view of a liquid-sealing shaft seal apparatus
in a rotary electrical machine according to a first embodiment of the present invention;
FIG. 1B is a perspective view of a portion taken from FIG. 1A;
FIG. 2 is an axial cross-sectional view of a liquid-sealing shaft seal apparatus in
a rotary electrical machine according to a second embodiment of the present invention;
FIG. 3 is an axial cross-sectional view of a liquid-sealing shaft seal apparatus in
a rotary electrical machine according to a third embodiment of the present invention;
FIG. 4 is an axial cross-sectional view of a liquid-sealing shaft seal apparatus in
a rotary electrical machine according to a fourth embodiment of the present invention;
FIG. 5 is an axial cross-sectional view of a liquid-sealing shaft seal apparatus in
a rotary electrical machine according to a fifth embodiment of the present invention;
and
FIG. 6 is an axial cross-sectional view on an example of a conventional shaft seal
apparatus.
[0015] Embodiments of the present invention will be described herebelow with reference to
the accompanying drawings.
(First Embodiment)
[0016] FIG. 1A is an axial cross-sectional view of a liquid-sealing shaft seal apparatus
in a rotary electrical machine according to a first embodiment of the present invention.
[0017] Referring to FIG. 1A, numeral 1 denotes a rotation shaft, and numeral 2 denotes a
frame forming the exterior of a rotary electrical machine. The rotation shaft 1 is
rotatably journaled by bearings (not shown) mounted to the frame 2. Numeral 3 is a
brush holder. The brush holder 3 is robustly and hermetically fixed to the frame 2,
and is mounted in such a manner as to close a liquid atmosphere space S1 and a non-liquid
atmosphere space S2 in the rotary electrical machine.
[0018] In space portions on the side of a bore of the brush holder 3 in the axial direction,
two brush seals spaced away from each other via a cavity 10 to be described later
are stored. Namely, there are stored two-stage brush seals formed of a brush seal
4a on the side of the liquid atmosphere S1 and a brush seal 4b on the side of the
non-liquid atmosphere S2. The brush seals 4a, 4b each are formed in the manner that
a brush 5 is clamped by a brush clamp 6. The brush seal 4a, 4b each is formed such
that multiple brush segments circumferentially split are combined into an annular
state as an array, and that two arrays are arranged by shifting circumferentially
split planes of the brush segments.
[0019] For example, with reference to FIG. 1B, the brush seal 4a has a structure formed
of two brush seal discs 4a1 and 4a2 overlapped with each other. The one brush seal
disc 4a1 is formed of tri-sectional brush seal pieces or segments 4a11, 4a12, and
4a13 circumferentially split. Similarly, the other brush seal disc 4a2 is formed of
tri-sectional brush seal pieces or segments 4a21, 4a22, and 4a23. A respective split
plane of the brush seal disc 4a1, such as a split plane between the brush seal pieces
4a11 and 4a13, and a respective split plane of the other brush seal disc 4a2, such
as a split plane between the brush seal pieces 4a21 and 4a22 are shifted by, for example,
60 degrees from each other in the circumferential direction.
[0020] In FIG. 1A, numeral 7 denotes a resin sheet packing formed of a resin sheet, such
as Teflon (registered trademark). More specifically, the respective packing 7 is formed
such that, similarly as the brush seal, multiple segments circumferentially split
are combined in an annular state, and is mounted on each of axial sidewalls on both
sides of the respective brush seals 4a, 4b such that an initial gap thereof with the
rotation shaft 1 is zero. For example, as shown in FIG. 1B, a packing plate 7b of
the packing 7 is so mounted on an axial sidewall of the brush seal 4a that the sprit
planes of the packing segments 7b1, 7b2 and 7b3 are circumferentially shifted with
respect to those of the segments 4a11, 4a12 and 4a13 of the brush seal 4a. The packing
plate 7b has a bore 7bb contacting with the rotation shaft 1, and the packing plate
7a is formed in the similar manner as the plate 7b. Numeral 8 denotes a spacer inserted
in an axial portion between the brush seals 4a and 4b axially provided in the two
stages. Numeral 9 denotes a holding plate fixed with a bolt (not shown) on an axial
sidewall of the brush holder 3 to fix the brush seals 4a and 4b, packing 7, and spacer
8, which are stored in the brush holder 3, into the brush holder 3.
[0021] Numeral 10 denotes a cavity as described above, which is provided by the spacer 8
between the brush seals 4a and 4b axially provided in the two stages. The cavity 10
is a space having an external diameter larger than that of the sealing plane which
can reduce the flow of gas along the periphery of the rotation shaft 1 generated with
the rotation of the rotation shaft 1. Numeral 11 denotes a through-hole provided on
the side of the external diameter of the brush holder 3. The through-hole 11 is configured
to allow communication of pressure between the axial atmosphere spaces S1 and S2 of
the rotary electrical machine separated by the brush holder 3, thereby to keep the
pressures therein equal. Numeral 12 is a liquid returning pass that continuously extends
through the spacer 8, the brush holder 3, and the holding plate 9. The liquid returning
pass 12 is thus formed to return liquid QL, which has leaked into the cavity 10 from
the liquid atmosphere space S1, to the liquid atmosphere space S1. Exterior portions
of an axial-end bore portion 3a of the brush holder 3 and a bore portion 9a of the
holding plate 9, respectively, are largely chamfered. This prevents liquid from accumulating
in gaps between the respective exterior portions and the rotation shaft 1, but falls
down under gravity.
[0022] Operation of the present embodiment will be described herebelow.
[0023] While the liquid atmosphere space S1 in the interior of the frame 2 of the rotary
electrical machine enters the state in which the liquid is dispersed by the rotation
of the rotation shaft 1, a large amount of dispersing liquid is sealed by the brush
seal 4 on the liquid atmosphere S1. However, part of the dispersing liquid passes
through, for example, gaps between the brushes 5 of the brush seal 4a and between
the brushes 5 and the rotation shaft 1 and leaks as a leakage liquid QL into the cavity
10. In this event, the resin sheet packing 7 is deformed by the holding plate 9 being
press tightened against the brush holder 3, thereby to seal gaps with the brush holder
3, the holding plate 9, and the brush clamp 6. Consequently, liquid leakage from a
gap between the rear face of the brush seal 4a and the brush holder 3 can be prevented.
In addition, since the initial gap with the rotation shaft 1 is set to zero, initial
abrasion is caused when the rotation shaft 1 rotates. Thereby, the gaps with the rotation
shaft 1 and the resin sheet packing 7 are reduced to minimum gaps in size set in consideration
factors including, for example, whirling resulting from eccentricity and the like
of the rotation shaft 1, and the area of contact between the liquid and the brush
5 of the brush seal 4a is minimized. Therefore, since the liquid is permeated into
the brush 5 of the brush seal 4a, the amount of the liquid QL leaking into the cavity
10 is significantly reduced. Moreover, since the cavity 10 exists, the leaked leakage
liquid is not influence by the rotation of the rotation shaft 1, but falls in the
gravitation direction and then flows into the liquid returning pass 12, whereby the
liquid QL is returned into the liquid atmosphere space S1.
[0024] In addition, the liquid atmosphere space S1 and the non-liquid atmosphere space S2
are in communication with each other through the through-hole 11, so that the pressure
is the same in the spaces S1 and S2. Accordingly, no differential pressure is applied
to the brush seal 4a, 4b, so that the amount of leakage liquid QL is not increased.
Further, since the axial-end bore portion 3a of the brush holder 3 and the bore portion
9a of the holding plate 9 are largely chamfered to form an inclined plane, the liquid
does not accumulates in the gaps between the respective chamfered portions and the
rotation shaft 1. Consequently, the amount of liquid possibly in contact with the
brush 5 of the brush seal 4a can be reduced.
[0025] As described above, according to the present embodiment, it is possible to reduce
the amount of leakage liquid QL leaking through the brush seal 4a through the resin
sheet packing 7, the axial-end bore portion 3a of the brush holder 3, the bore portion
9a of the holding plate 9, and the through-hole 11. Further, with the cavity 10 being
arranged, the leakage liquid having leaked through the brush seal 4a on the side of
the liquid atmosphere is prevented from dispersing in the cavity 10, but is guided
to fall along the gravitation direction. Thereby, the liquid QL can be returned to
the liquid atmosphere space S1 through the liquid returning pass 12. Consequently,
the amount of liquid leaking into the non-liquid atmosphere space S2 through the brush
seal 4b can be significantly reduced.
(Second Embodiment)
[0026] FIG. 2 is an axial cross-sectional view of a liquid-sealing shaft seal apparatus
in a rotary electrical machine according to a second embodiment of the present invention.
Like reference characters are used in the drawing and description for portions identical
to those in the first embodiment shown in FIG. 1.
[0027] Referring to FIG. 2, numeral 3 is a brush holder robustly and hermetically fixed
to the frame 2, and is mounted in such a manner as to close a liquid atmosphere space
Q and a liquid atmosphere space R in the rotary electrical machine. In space portions
on the side of the bore of the brush holder 3 in the axial direction, three brush
seals spaced away from one another via cavities 10a and 10b to be described later
are stored. Namely, there are stored three-stage brush seals formed of a brush seal
4c on the side of the liquid atmosphere Q, a brush seal 4d on the side of the liquid
atmosphere R, and an inbetween-stage brush seal 4e. Similarly as shown in FIG. 1B,
the brush seals 4c, 4d, and 4e each is formed in the manner that the brush 5 is clamped
by the brush clamp 6. The brush seals 4c, 4d, and 4e each is formed such that multiple
brush segments circumferentially split are combined into an annular state, and that
two arrays are arranged by circumferentially shifting split planes of the respective
brush segments from each other. Numeral 7 denotes resin sheet packing plates each
formed of a resin sheet, such as Teflon (registered trademark). More specifically,
the respective packing 7 is formed such that, similarly as the brush seal, multiple
packing segments split in the circumferential direction are combined in an annular
state. The resin sheet packing 7 is so mounted on each of axial sidewalls on both
sides of the respective three-stage brush seals 4c, 4d, and 4e that the sprit planes
of the packing segments are circumferentially shifted with respect to those of the
brush seal segments and that an initial gap thereof with the rotation shaft 1 is zero.
Numeral 8 denotes a spacer inserted in each of axial inbetween portions of the brush
seals 4d, 4e and 4c arranged in the three stages in the axial direction. Numeral 9
denotes a holding plate, which is fixed with a bolt (not shown) on an axial sidewall
of the brush holder 3 to fix the brush seals 4d, 4e, and 4c, the resin sheet packing
7, and the spacer 8, which are stored in the brush holder 3, into the brush holder
3. Numerals 10a and 10b, respectively, denote the cavities as mentioned above, which
are provided in respective inbetween portions of the brush seals 4d, 4e and 4c arranged
in the three stages in the axial direction. The cavities 10a, 10b each is a space
having an external diameter larger than that of the brush seals for reducing the flow
of gas in the periphery of the rotation shaft 1 generated in conjunction with the
rotation of the rotation shaft 1. Numeral 11 denotes a through-hole provided on the
side of the external diameter of the brush holder 3. The through-hole 11 is formed
to allow communication of pressure between the axial atmosphere spaces Q and R of
the rotary electrical machine which are separated by the brush holder 3, thereby to
keep the pressures on both outer sides of the brush seals 4a, 4b equal. Numerals 12a
and 12b, respectively, are liquid returning passes of return liquids QL and RL. The
liquid returning pass 12a on one side continuously extends through the spacer 8, brush
holder 3, and holding plate 9 toward the side of the liquid atmosphere Q from the
cavity 10a on the side of the liquid atmosphere Q, which is one of the two cavities
located in the axial direction. The liquid returning pass 12b on the other side continuously
extends through the spacer 8 and brush holder 3 toward the side of the liquid atmosphere
R from the cavity 10b on the side of the liquid atmosphere R, which is the other one
of the two cavities located in the axial direction. The inner diameter side shape
of the axial-end portion 3a of the brush holder 3 and the inner diameter side shape
of the axial-end portion 9a of the holding plate 9, respectively, are largely chamfered
to form inclined planes.
[0028] Operation of the present embodiment will be described herebelow.
[0029] The present embodiment of the liquid-sealing shaft seal apparatus in the rotary electrical
machine, which is constructed as described above, operates as follows. While the liquid
QL in the liquid atmosphere Q is dispersed in the liquid atmosphere space Q in conjunction
with the rotation of the rotation shaft 1, the gap is sealed by the brush seal 4c
on the side of liquid atmosphere Q. In this case, as in the first embodiment, the
amount of the leakage liquid QL leaking from the brush seal 4c on the side of the
liquid atmosphere Q is reduced to be smaller than in the conventional techniques.
This is implemented by the functions of the resin sheet packings 7, the shape of the
brush-holder axial-end bore portion 3a, and the structure including the through-hole
11. In addition, by virtue of the cavity 10a, the leakage liquid QL having leaked
into the cavity 10a does not disperse in the cavity 10a, but is guided to flow down
under gravity, whereby the liquid is returned into the liquid atmosphere space Q through
the returning pass 12a for the liquid QL. Consequently, the amount of leakage liquid
QL leaking through the brush seal 4e to the side of the cavity 10b is significantly
reduced.
[0030] On the other hand, while the liquid on the side of the liquid atmosphere R is dispersed
in the liquid atmosphere space R in conjunction with the rotation of the rotation
shaft 1, the gap is sealed by the brush seal 4d on the side of liquid atmosphere R.
In this case, however, similarly as in the case of the brush seal 4c on the side of
the liquid atmosphere Q, the amount of leakage liquid RL leaking from the brush seal
4d on the side of the liquid atmosphere R is smaller than in the conventional techniques.
This is implemented by the functions of the resin sheet packings 7, the shape of the
bore portion 9a of the holding plate 9, and the structure including the through-hole
11. In addition, by virtue of the cavity 10b, the leakage liquid RL having leaked
into the cavity 10b does not disperse in the cavity 10a, but is guided to flow down
under gravity, whereby the liquid is returned into the liquid atmosphere space R through
the returning pass 12b for the liquid RL. Consequently, the amount of leakage liquid
RL leaking through the brush seal 4e to the side of the cavity 10b is significantly
reduced.
[0031] As described above, according to the present embodiment, the respective amounts of
leakage liquid leaking through the brush seal 4e can be reduced. This is implemented
by the functions of the resin sheet packings 7, the shapes of the axial-end bore portion
3a of the brush holder 3 and the bore portion 9a of the holding plate 9, and the structure
including the through-hole 11. In addition, by virtue of cavities 10a, 10b, the respective
leakage liquids QL, RL having leaked through the brush seals 4c, 4d on the liquid
atmosphere do not disperse in the cavities 10a, 10b, but flows down in the gravitation
direction, whereby the liquids can be returned into the liquid atmosphere spaces Q,
R through the liquid returning passes 12a, 12b. Consequently, the amount of leakage
liquid leaking through the brush seal 4e to the other liquid atmosphere space, and
the amount of mixture between the liquids Q and R can be significantly reduced.
(Third Embodiment)
[0032] FIG. 3 is an axial cross-sectional view of a liquid-sealing shaft seal apparatus
in a rotary electrical machine a third embodiment of according to the present invention.
Like reference characters are used in the drawing and description for portions identical
to those in the first embodiment shown in FIG. 1.
[0033] Referring to FIG. 3, numeral 1 denotes a rotation shaft, numeral 2 denotes a frame,
and numeral 3 is a brush holder. The brush holder 3 is robustly, hermetically fixed
to the frame 2, and is mounted in such a manner as to close a liquid atmosphere space
Q and a liquid atmosphere space R in the rotary electrical machine. In space portions
on the side of the bore of the brush holder 3 in the axial direction, three brush
seals spaced away from one another via cavities 10a and 10b to be described later
are stored. Namely, there are stored three-stage brush seals formed of a brush seal
4c on the side of the liquid atmosphere Q, a brush seal 4d on the side of the liquid
atmosphere R, and an inbetween-stage brush seal 4e. Similarly as shown in FIG. 1B,
the brush seals 4c, 4d, and 4e each are formed in the manner that the brush 5 is clamped
by the brush clamp 6. The brush seals 4c, 4d, and 4e each are formed such that multiple
segments circumferentially split are combined into an annular state, and that two
arrays are arranged by circumferentially shifting split planes from each other. Numeral
7 denotes resin sheet packings each formed of a resin sheet. More specifically, the
respective packing 7 is formed such that, similarly as the brush seal, multiple packing
segments split in the circumferential direction are combined in an annular state.
Each of the resin sheet packings 7 is so mounted on axial sidewalls of the respective
three-stage brush seals 4c, 4d, and 4e that the split planes of the packing segments
are circumferentially shifted with respect to those of the brush seal segments and
that an initial gap thereof with the rotation shaft 1 is zero. Numerals 8a, 8b denote
spacers each inserted in each of axial inbetween portions of the brush seals 4d, 4e
and 4c arranged in the three stages in the axial direction. Numeral 9 denotes a holding
plate, which is fixed with a bolt (not shown) on an axial sidewall of the brush holder
3 to fix the brush seals 4c, 4d, and 4e, the resin sheet packing 7, and the spacers
8a and 8b, which are stored in the brush holder 3, into the brush holder 3. Numerals
10a and 10b, respectively, denote the cavities as mentioned above, which are provided
in respective inbetween portions of the brush seals 4c, 4d and 4e provided in the
three stages in the axial direction. The cavities 10a, 10b each are a space having
an external diameter larger than that of the seal plate for reducing the flow of gas
in the periphery of the rotation shaft 1 generated in conjunction with the rotation
of the rotation shaft 1. Numeral 13 denotes a cavity through-hole provided to continuously
pass through the spacer 8a, the brush holder 3, the frame 2, and further to extend
to the exterior of the frame 2 of the rotary electrical machine from the cavity 10a
on the side the liquid atmosphere Q. Numeral 14 denotes another cavity through-hole
provided to continuously pass through the spacer 8b, the brush holder 3, the frame
2, and further to extend to the exterior of the frame 2 of the rotary electrical machine
from the cavity 10b on the side the liquid atmosphere R.
[0034] Operation of the present embodiment will be described herebelow.
[0035] The present embodiment of the liquid-sealing shaft seal apparatus in the rotary electrical
machine, which is constructed as described above, operates as follows. While the liquid
in the liquid atmosphere Q is dispersed in the liquid atmosphere space Q in conjunction
with the rotation of the rotation shaft 1, the gap is sealed by the brush seal 4c
on the side of liquid atmosphere Q. In this case, as in the first embodiment, the
amount of the leakage liquid QL leaking from the brush seal 4c on the side of the
liquid atmosphere Q into the cavity 10a is reduced to be smaller than in the conventional
techniques by the functions of the resin sheet packings 7. In addition, when a pressure
higher than that in the liquid atmosphere space Q is applied to the cavity 10a through
the cavity through-hole 13 from the outside of the rotary electrical machine, a pressure
in the reverse direction with respect to the leakage direction of the leakage liquid
QL is exerted on the brush seal 4c. Thereby, the leakage liquid QL having leaked through,
for example, the gap with the brush 5 constituting the brush seal 4c and the gap between
the brush 5 and the rotation shaft 1 is returned to the liquid atmosphere space Q.
Consequently, the leakage liquid QL is significantly reduced in amount, and does not
accumulate in the cavity 10a.
[0036] On the other hand, while the liquid in the liquid atmosphere R disperses in the liquid
atmosphere space R in conjunction with the rotation of the rotation shaft 1, the gap
is sealed by the brush seal 4d on the side of liquid atmosphere R. In this case, as
in the first embodiment, the amount of leakage liquid RL leaking from the brush seal
4d on the side of the liquid atmosphere R into the cavity 10b is reduced to be smaller
than in the conventional techniques by the functions of the resin sheet packings 7.
In addition, when a pressure higher than that in the liquid atmosphere space R is
applied to the cavity 10b through the cavity through-hole 14 from the outside of the
rotary electrical machine, a pressure in the reverse direction with respect to the
leakage direction of the leakage liquid RL is exerted on the brush seal 4d. Thereby,
the leakage liquid RL having leaked through, for example, the gap with the brush 5
constituting the brush seal 4d and the gap between the brush 5 and the rotation shaft
1 is returned to the liquid atmosphere space R. Consequently, the leakage liquid RL
is significantly reduced in amount, and does not accumulate in the cavity 10b.
[0037] In a general rotary electrical machine, a cooling fan is provided for intra-machine
ventilation, so that the intra-machine pressure is negative with respect to the atmospheric
pressure. In this case, through-holes corresponding to the cavity through-holes 13
and 14 are opened to the atmosphere, so that the pressure is increased, whereby effects
equivalent to the case of pressurization can be obtained.
[0038] As described above, according to the present embodiment, in addition to the effects
of the resin sheet packings 7, the cavity through-holes 13 and 14 are either applied
with pressure or opened to the atmosphere. In this case, the brush seals 4c and 4d,
respectively, are applied with pressure differences in the reverse direction with
respect the leakage directions of the leakage liquids QL and RL. Consequently, the
respective liquids do not leak through the brush seal 4e into the cavities 10a and
10b, nor do the respective liquids mix into one another. Further, when the cavity
through-holes 13 and 14 are opened to the atmosphere, a compressor is not necessary,
thereby simplifying the construction and reducing the cost thereof.
(Fourth Embodiment)
[0039] FIG. 4 is an axial cross-sectional view of a liquid-sealing shaft seal apparatus
in a rotary electrical machine according to a fourth embodiment of the present invention.
Like reference characters are used in the drawing and description for portions identical
to those in the first embodiment shown in FIG. 1.
[0040] Referring to FIG. 4, numeral 1 denotes a rotation shaft, and numeral 2 denotes a
frame. Numeral 3 is a brush holder robustly and hermetically fixed to the frame 2.
The brush holder 3 is mounted in such a manner as to close a liquid atmosphere space
S1 and a non-liquid atmosphere space S2 in the rotary electrical machine. In space
portions on the side of the bore of the brush holder 3 in the axial direction, two
brush seals spaced away from each other via a cavity 10 to be described later are
stored. Namely, there are stored two-stage brush seals formed of a brush seal 4a on
the side of the liquid atmosphere S1 and a brush seal 4b on the side of the non-liquid
atmosphere S2. Similarly as shown in FIG. 1B, the brush seals 4a, 4b are each formed
in the manner that the brush 5 is clamped by the brush clamp 6. The brush seals 4a,
4b are each formed such that multiple segments circumferentially split are combined
into an annular state, and that two arrays are arranged by circumferentially shifting
split planes from each other. Numeral 7 denotes a resin sheet packing formed of a
resin sheet. More specifically, the respective packing 7 is formed such that, similarly
as the brush seals 4a, 4b, multiple packing segments split in the circumferential
direction are combined in an annular state. The resin sheet packing 7 is so mounted
on each of axial sidewalls on both sides of the respective two-stage brush seals 4a
and 4b that the split planes of the packing segments are circumferentially shifted
with respect to those of the brush seal segments and that an initial gap thereof with
the rotation shaft 1 is zero. Numeral 15 denotes a short brush seal that has a length
not contacting the rotation shaft 1. Preferably, the short brush seal 15 is formed
such that a short brush clamp 17 clamps the external diameter side of a short brush
16. In this case, the short brush 16 has a length enabling forming the cavity 10 that
serves as a space that reduces the flow of gas in the periphery of the rotation shaft
1 which is generated in conjunction with the rotation of the rotation shaft 1. As
the above-described brush seal, the short brush seal 15 is formed such that multiple
segments split in the circumferential direction are combined in an annular state,
and is mounted in an axial portion between the brush seals 4a and 4b arranged in the
two stages in the axial direction. The short brush clamp 17 has multiple holes H in
the radial direction. Numeral 11 denotes a through-hole to communicate between the
same spaces S1 and S2 as in the first embodiment in FIG. 1. Numeral 12 is a liquid
returning pass that continuously extends through the brush holder 3 and the holding
plate 9 from the rear face of the short brush seal 15 to the liquid atmosphere space
S1. Also the shapes the brush-holder axial-end bore portion 3a of the brush holder
3 and the bore portion 9a of the holding plate 9 are the same as in the first embodiment
shown in FIG. 1.
[0041] Operation of the present embodiment will be described herebelow.
[0042] The present embodiment of the liquid-sealing shaft seal apparatus in the rotary electrical
machine, which is constructed as described above, operates as follows. While the liquid
in the liquid atmosphere S1 is dispersed in the liquid atmosphere space S1 in conjunction
with the rotation of the rotation shaft 1, the gap is sealed by the brush seal 4a
on the side of liquid atmosphere S1. In this case, as in the first embodiment, the
amount of leakage liquid leaking from the brush seal 4a on the side of the liquid
atmosphere S1 into the cavity 10 is reduced to be smaller than in the conventional
techniques by the functions of the resin sheet packings 7 and the shape of the bore
portion 9a of the holding plate 9. In addition, most of the liquid having leaked to
the cavity 10 is captured by the short brush 16, and permeates into the short brush
16 through capillarity or capillary action. The short brush 16 has a length not contacting
the rotation shaft 1. The liquid permeated in the short brush 16 is directed under
gravity to flow downward along the short brush clamp 17, and then is returned to the
liquid atmosphere space S1 through the liquid returning pass 12 from the holes H in
the radial direction provided in the short brush clamp 17. Consequently, the liquid
leaking through the brush seal 4b into the non-liquid atmosphere space S2 is significantly
reduced.
[0043] As described above, according to the present embodiment, in addition to the effects
of the resin sheet packings 7 and the shape of the bore portion 9a of the holding
plate 9, even a small amount of liquid having leaked through the brush seal 4a is
securely trapped by the short brush seal 15 provided in the cavity 10, and then is
returned to the liquid atmosphere space S1 by using the liquid returning pass 12.
Consequently, liquid sealing performance in the case of a rotary electrical machine
containing the liquid is significantly improved. Further, even mist-state liquid can
be securely captured through the capillary action of the short brush 16. Consequently,
advantages can be obtained in that the size of the cavity 10 can be reduced, and hence
the overall size of the brush seal apparatus can be reduced.
(Fifth Embodiment)
[0044] FIG. 5 is an axial cross-sectional view of a liquid-sealing shaft seal apparatus
in a rotary electrical machine according to a fifth embodiment of the present invention.
Like reference characters are used in the drawing and description for portions identical
to those in the first embodiment shown in FIG. 1.
[0045] Referring to FIG. 5, numeral 1 denotes a rotation shaft, and numeral 2 denotes a
frame. Numeral 3 is a brush holder robustly and hermetically fixed to the frame 2.
The brush holder 3 is mounted in such a manner as to close a liquid atmosphere space
S1 and a non-liquid atmosphere space S2 in the rotary electrical machine. In space
portions on the side of the bore of the brush holder 3 in the axial direction, two
brush seals spaced away from each other via a cavity 10 to be described later are
stored. Namely, there are stored two-stage brush seals formed of a brush seal 4a on
the side of the liquid atmosphere S1 and a brush seal 4b on the side of the non-liquid
atmosphere S2. Similarly as shown in FIG. 1B, the brush seals 4a, 4b are each formed
in the manner that the brush 5 is clamped by the brush clamp 6. The brush seals 4a,
4b are each formed such that multiple segments circumferentially split are combined
into an annular state, and that two arrays are arranged by circumferentially shifting
split planes from each other. Numeral 7 denotes a resin sheet packing formed of a
resin sheet. More specifically, the respective packing 7 is formed such that, similarly
as the brush seals 4a, 4b, multiple packing segments split in the circumferential
direction are combined in an annular state. The resin sheet packing 7 is so mounted
on each of axial sidewalls on both sides of the respective two-stage brush seals 4a
and 4b that the split planes of the packing segments are circumferentially shifted
with respect to those of the brush seal segments and that an initial gap thereof with
the rotation shaft 1 is zero. Numeral 18 denotes a spacer formed of a porous material,
and is inserted between the brush seals 4a and 4b arranged in two stages in the axial
direction. Numeral 9 denotes the same holding plate as that shown in FIG. 1. Numeral
10 denotes the cavity as described above, which has an external diameter larger than
that of the seal plane for reducing the flow of gas in the periphery of the rotation
shaft 1 generated with the rotation of the rotation shaft 1 in a space surrounded
by the resin sheet packings 7, which is defined by the sidewalls of the brush seal,
the rotation shaft 1, and the porous spacer 18. Numeral 11 denotes the same through-hole
as that in the first embodiment shown in FIG. 1. Numeral 12 is the same liquid returning
pass as that in the fourth embodiment shown in FIG. 4, and a porous material 19 is
filled therein.
[0046] Operation of the present embodiment will be described herebelow.
[0047] The present embodiment of the liquid-sealing shaft seal apparatus in the rotary electrical
machine, which is constructed as described above, operates as follows. While the liquid
in the liquid atmosphere S1 is dispersed in the liquid atmosphere space S1 in conjunction
with the rotation of the rotation shaft 1, the gap is sealed by the brush seal 4a
on the side of liquid atmosphere S1. In this case, as in the first embodiment, the
amount of the leakage liquid QL leaking from the brush seal 4a on the side of the
liquid atmosphere S1 into the cavity 10 is reduced to be smaller than in the conventional
techniques by the functions of the resin sheet packings 7 and the shape of the bore
portion 9a of the holding plate 9. In addition, most of the liquid having leaked into
the cavity 10 is captured by the porous spacer 18 arranged on the side of the external
diameter of the cavity 10. The liquid thus captured is directed under gravity to flow
downward through the interior of the porous spacer 18, and then is returned to the
liquid atmosphere space S1 through the porous filler material 19 filled into the liquid
returning pass 12 arranged below the cavity 10. Consequently, the amount of liquid
leaking through the brush seal 4b into the non-liquid atmosphere space S2 is significantly
reduced.
[0048] As described above, according to the present embodiment, in addition to the effects
of the resin sheet packings 7 and the porous filler material 19, even a small amount
of liquid having leaked through the brush seal 4a is securely captured by the porous
spacer 18 formed of the porous material and provided in the cavity 10. Further, the
liquid is guided to return to the liquid atmosphere space S1 through the porous filler
material 19 filled in the liquid returning pass 12. Thereby, the amount of liquid
leaking through the brush seal 4b into the non-liquid atmosphere space S2 is significantly
reduced. Consequently, liquid sealing performance is significantly improved. Further,
as in the fourth embodiment shown in FIG. 4, even a mist-state liquid in the cavity
10 can be securely captured through the spacer 18 formed of the porous material. Consequently,
the size of the cavity 10 can be reduced, and hence the overall size of the brush
seal apparatus can be reduced.
1. A liquid-sealing shaft seal apparatus comprising:
a rotation shaft (1);
brush seals (4a, 4b) arranged in such a manner as to contact and surround the rotation
shaft (1); and
a brush holder (3) which holds the brush seals (4a, 4b), characterized in that
more than one line of brush seals (4a, 4b) are arranged in the axial direction of
the rotation shaft through a cavity (10); and
the brush holder (3) is provided with a liquid returning pass (12) to return a liquid
having leaked through the brush seals (4a, 4b) into the cavity (10) to the side of
an atmosphere (S1) in which a liquid is present as a sealing target.
2. A liquid-sealing shaft seal apparatus according to claim 1, characterized in that the plurality of brush seals (4a, 4b) are at least three brush seals (4c, 4d, 4e)
arranged through two cavities (10a, 10b) in the axial direction of the rotation shaft
(1).
3. A liquid-sealing shaft seal apparatus according to any one of claims 1 and 2, characterized in that at least one packing plate (7a, 7b) which is formed of an annular resin sheet having
an external diameter larger than a brush portion (5) of the brush seals (4a, 4b) and
having a bore (7bb) that contacts with the rotation shaft (1) is provided on at least
one of axial sidewalls of each of the plurality of brush seals (4a, 4b).
4. A liquid-sealing shaft seal apparatus according to any one of claims 1 to 3, characterized in that the brush holder (3) further provides a through-hole (11) which connects spaces (S1,
S2) on two axial sides of the brush seals (4a, 4b) provided around the rotation shaft
(1).
5. A liquid-sealing shaft seal apparatus according to any one of claims 1 to 4, characterized in that at least one of an inner diameter side shape (9a) of the holding plate (9) and an
inner diameter side shape (3a) of an axial side surface of the brush holder (3) on
a side axially opposite to the holding plate (9) has an inclined plane which does
not include a flat face on the inner diameter side and has a larger internal diameter
on a shaft end side than an internal diameter on an axially center side facing the
cavity (10).
6. A liquid-sealing shaft seal apparatus according to any one of claims 1 to 5, characterized in that each line of the brush seals (4a, 4b) is formed in a manner that at least two brush
seal plates (4a1, 4a2) each formed of a plurality of brush seal segments (4a11, 4a12,
4a13, 4a21, 4a22, 4a23) combined into an annular state are overlapped with one another,
and split planes of the brush seal segments are shifted from one another in a circumferential
direction thereof.
7. A liquid-sealing shaft seal apparatus according to any one of claims 1 to 6, characterized in that a brush (16) having a length not contacting the rotation shaft (1) is arranged in
the cavity (10) provided with the liquid returning pass (12) between the plurality
of brush seals (4a, 4b) arranged in the axial direction of the rotation shaft (1).
8. A liquid-sealing shaft seal apparatus according to any one of claims 1 to 6, characterized in that a spacer (18) formed of a porous material and having a bore not contacting the rotation
shaft (1) is arranged in the cavity (10) provided with the liquid returning pass (12)
configured between the plurality of brush seals (4a, 4b) arranged in the axial direction
of the rotation shaft (1).
9. A liquid-sealing shaft seal apparatus according to any one of claims 1 to 8, characterized in that a porous material (19) is arranged in the liquid returning pass (12) provided between
the plurality of brush seals (4a, 4b) in the axial direction of the rotation shaft
(1).
10. A liquid-sealing shaft seal apparatus comprising:
a rotation shaft (1);
brush seals (4a, 4b) arranged in such a manner as to contact and surround the rotation
shaft (1); and
a brush holder (3) which holds the brush seals (4a, 4b), characterized in that
more than one line of brush seals (4a, 4b) are arranged in an axial direction of the
rotation shaft (1) through a cavity (10); and
a pressure in the cavity (10) is higher than a pressure on the side of an atmosphere
(S1) in which a liquid is present as a sealing target.
11. A liquid-sealing shaft seal apparatus according to claim 10, characterized in that
the pressure on the side of the atmosphere (Q) containing the liquid is maintained
to be negative, and
the pressure in the cavity (10a, 10b) is opened to the air atmosphere.
12. A rotary electrical machine using liquids such as a bearing lubrication oil and a
seal oil for sealing intra-machine refrigerant gases, characterized by comprising the liquid-sealing shaft seal apparatus according to any one of claims
1 to 11.